PLEASE HELP ME. please explain your answer as well

Little’s law firm has just one lawyer. customers arrive randomly at an average rate of 6 per 8 hour workday. service times have a mean of 50 minutes and a standard deviation of 20 minutes. how long does a customer spend at little’s law firm on average?

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)

The difference of two numbers is 40. find the numbers if 0.3 parts of one number is equal to 37.5% of the other one.